This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Bacteriophages, herpesviruses and other large dsDNA viruses contain molecular machines that pump DNA into preassembled procapsids, triggering maturation with an associated cascade of particle size change, release of packaging enzymes, binding of proteins for cell association and activation of the particles for infection. These events are associated with capsid pressures exceeding, by 10-fold, that of bottled champagne, and are detected by a protein switch that transduces a signal from inside to outside of the particle.